1. Field of the Invention
The present invention relates to a cassette compartment mechanism, in particular to a cassette compartment mechanism through which a video cassette having a lid, such as a video cassette for containing a video recording tape according to a standard of a so-called `8 millimeter video tape` is handled in a video recording/reproducing apparatus. A video cassette which includes a video tape of the 8 millimeter video standard will be referred to as `8-mm video cassette`, hereinafter.
Related typical standards will now be listed below:
EIAJ (Electronics Industries Association of Japan), No. CP-3103, entitled 8-mm Video.8-mm Magnetic Tape Helical Scan Video Cassette System;
JIS (Japanese Industrial Standard), No. JISC 5583 (1992), entitled 8-mm Video.8-mm Magnetic Tape Helical Scan Video Cassette System; and
IEC (International Electrotechnical Commission publication), No. 843 (1987), entitled Helical Scan Video Cassette System using 8-mm Magnetic Tape Video-8. Further, a separate edition of Electronics Life, a journal of Nippon Hoso Shuppan Kyokai (Japan Broadcasting Publishing Society) published Jun. 20, 1985, entitled The Latest Video, from 8-mm video to high fidelity (HiFi) video discloses a structure of the 8-mm video cassette.
2. Related Art
In the video recording/reproducing apparatus, the cassette compartment mechanism holds the video cassette, containing a video tape therein, and transports the thus-held cassette between an inserted position and an operation position. The inserted position is a position at which a user may put the cassette in the video recording/reproducing apparatus, and from which position the user may withdraw the inserted cassette so as to take it out of the apparatus. While the cassette is positioned at the above-mentioned operation position, a part of the recording tape contained in the cassette faces a recording/reproducing head provided in the apparatus.
Ordinarily, the cassette compartment mechanism is provided with a cassette holder unit and a supporting arm unit. Into the cassette holder unit, the video cassette is inserted by an operator and the cassette holder unit then holds the thus-inserted cassette. The supporting arm unit supports the cassette holder unit and move the holder unit so as to cause it either to approach a base (chassis) or to go away therefrom. On the base, a mechanism for driving (winding) a recording tape contained in the cassette and the recording/reproducing head are mounted.
With reference to FIG. 1, an example of a cassette compartment mechanism 20 will now be described in general. The cassette compartment mechanism 20 shown FIG. 1 is a cassette compartment mechanism of a hop up type. In the mechanism 20, a holder unit 210 acts as the above-mentioned cassette holder unit and an arm unit 230 acts as the above-mentioned supporting arm unit. When a cassette 10 is loaded in a relevant recording/reproducing apparatus, an operator first inserts the cassette 10 into the holder unit 210 along a direction X1 shown in FIG. 1. Then, the operator pushes the holder unit 210 at positions A1 and A2 downward. Thus, the holder unit 210 having the cassette 10 therein is lowered from a top position (corresponding to the above-mentioned inserted position) to a bottom position (corresponding to the above-mentioned operation position) at which a tape contained in the cassette 10 can be wound through a tape winding mechanism of the recording/reproducing apparatus.
After the holder unit 210 is lowered to the bottom position, a projection 216P of a lock lever 216 mounted on the holder unit 210 is engaged by a hook 302 formed on the base (chassis) 30, the holder unit 210 being thus connected to the base 30 through the engagement.
If the operator turns a release lever 217 in a direction B1 shown in FIG. 1, the turning of the lever 217 causes, through a not shown mechanism, the lock lever 216 to turn so that the engagement of the projection 216P with the hook 302 is released. As a result, since an upward force is applied to the holder unit 210 through a not shown mechanism in a state in which the holder unit 210 is located at the bottom position, the holder unit 210 is automatically raised to the top position through a certain mechanism.
Although not shown in the figure, the release lever 217 also has a projection thereon similar to the projection 216P provided on the lock lever 216 but projecting outward oppositely to the projection 216P. Further, another hook is also provided on the base 30. These projection and hook act similarly to and simultaneously with the above-described action of the projection 216P and hook 302 but at the opposite side with respect to holder unit 210. Thus, when the holder unit 210 is positioned at the bottom position, the holder unit 210 is connected at the two sides thereof to the base 30 through the engagements. The engagements prevent the holder unit 210 from being raised from the bottom position.
As it is well known, the 8-mm video cassette includes a case containing a recording tape and the case has a lid for preventing dust from coming into the case. With reference to FIGS. 2A and 2B, a structure of the typical 8-mm video cassette will now be described. The cassette 10 has the case 101 containing the recording tape 110 and the case 101 has the lid unit 102 in front thereof as shown in the drawings. The lid unit 102 includes a main lid 103 and a sub-lid 104. The sub-lid may be called `an inner lid`. The main lid 103 is supported on the case 101 rotatably about a axis shaft 105. The sub-lid 104 is rotatably supported on the main lid 103.
When the cassette 10 is inserted into the holder unit 210 of the cassette compartment mechanism 20 shown in FIG. 1, a nail member not shown in the drawings raises the main lid 103 as shown in FIG. 2B, through the cassette compartment mechanism. As a result, a front extending part of the recording tape 110 is exposed and thus the recording/reproducing head mounted on the base can access the part of the recording tape. The sub-lid 104 moves in response to the above-mentioned raised movement of the main lid 103 so that a front part of the sub-lid 104 is placed on a front part of the main lid 103 as shown in FIG. 2B. Thus, in an opened state shown in FIG. 2B of the lid unit 102 in which the part of the recording tape is exposed, the sub-lid 104 is lifted on the front part of the main lid 103. It seems that the provision of the sub-lid 103 is advantageous for preventing dust from coming into the case in a closed state shown in FIG. 2A of the lid unit 102.
A force is always applied to the main lid 103 through a not shown spring provided in the cassette 10. Thus, if the cassette 10 is being withdrawn from the holder unit 210, a not shown mechanism causes the above-mentioned nail member to be removed from the main lid 103 so that the main lid 103 automatically moves to cover the front of the case 101. Thus, the once exposed part of the recording tape 110 is covered by the main lid 103 and sub-lid 104 before the cassette is completely withdrawn from the holder unit 210 of the cassette compartment mechanism. The above-mentioned lid opening and closing operations due to the function of the nail member may be performed either in the process in which the cassette 10 is inserted into/withdrawn from the holder unit 210 or in the process in which the holder unit 210 is lowered/raised between the top position and bottom position.
In the structure of the 8-mm video cassette described above, the above-mentioned spring, which applied the force to the main lid 103 so as to move the main lid 103 to cover the recording tape, may change in its elastic capability due to aging. Thus, the above-mentioned force may become weakened. In such a case, even if the cassette 10 is being withdrawn from the holder unit 210 of the cassette compartment mechanism 20, the main lid 103 cannot automatically move to cover the recording tape. That is, the lid unit 102 is left in the state shown in FIG. 2B. Further, the same phenomenon may occur as a result of, for a certain reason, the sub-lid 104 is undesirably engaged with the main lid 103 in the state shown in FIG. 2B. Thus, the sub-lid 104 is prevented from smoothly sliding on the main lid 103 and thus the main lid 103 is not allowed to move downward to cover the recording tape.
The operator may attempt to withdraw the cassette 10 from the holder unit 210 so as to completely take out the cassette 10 from the holder unit 210, the lid unit 102 being in the state shown in FIG. 2B. If so, problems may occur, in which the main lid 103 and/or sub-lid 104 is engaged with one of members constituting the holder unit 210. In particular, the sub-lid 104 is lifted on the front part of the main lid 103 as shown in FIG. 2B in the opened state. Thus, the sub-lid 104 is projected upwardly and thus is likely to be undesirably engaged with a member of the holder unit 210. Thus, the cassette 10 cannot be withdrawn. In such a case, if the operator forcibly attempts to withdraw the cassette 10 from the holder unit 210, the lid unit 102 may be damaged.